Updating from 2.0.2 to 2.0.4

[itimtom]

Hi All,

I recently installed 2.0.2 Magento community version using Softaculous under Cpanel. 

I have also added a theme I purchased, and inserted some records in terms of Products.

So the 2.0.4 email arrives and I must now install an update.

I have downloaded the ZIP version from the links in the email from magento, unzipped it but now what do I do?

I cannot find any documentation.

Do I just FTP the whole unzipped package - every single file and overwrite whatever is there?

Do I need to be careful with any files in particular which now contain my settings/data online which could be overwritten if I ftp the whole unzipped package from Magento?

Please can anyone advise on what's the next thing I have to do with all the unzipped files.

I have been into the system upgrade, it comes up "Checking for New Version" - then comes up with the message "Sorry - we cant take that action right now".  So I retry and it does the same.

Thanks

Mark

[Dmitry_Fedyuk]

http://devdocs.magento.com/guides/v2.0/comp-mgr/bk-compman-upgrade-guide.html

[kennydlawrence]

.

[itimtom]

I sorted this out with the Keys - I hadnt entered the keys.

Now the problem is I cannot update because the Readiness check is failing with cron job and php errors.

Give me strength.

[Dmitry_Fedyuk]

Please publish a screenshot of the error messages